| /* (C) 2010-2012 by Harald Welte <laforge@gnumonks.org> |
| * |
| * All Rights Reserved |
| * |
| * SPDX-License-Identifier: GPL-2.0+ |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; either version 2 of the License, or |
| * (at your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License along |
| * with this program; if not, write to the Free Software Foundation, Inc., |
| * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| */ |
| |
| #include "config.h" |
| |
| #include <errno.h> |
| #include <stdint.h> |
| #include <string.h> |
| |
| #include <osmocom/core/utils.h> |
| #include <osmocom/core/linuxlist.h> |
| #include <osmocom/core/plugin.h> |
| |
| #include <osmocom/crypt/auth.h> |
| |
| /*! \addtogroup auth |
| * @{ |
| * GSM/GPRS/3G authentication core infrastructure |
| * |
| * \file auth_core.c */ |
| |
| static LLIST_HEAD(osmo_auths); |
| |
| static struct osmo_auth_impl *selected_auths[_OSMO_AUTH_ALG_NUM]; |
| |
| /*! Register an authentication algorithm implementation with the core |
| * \param[in] impl Structure describing implementation and it's callbacks |
| * \returns 0 on success, or a negative error code on failure |
| * |
| * This function is called by an authentication implementation plugin to |
| * register itself with the authentication core. |
| */ |
| int osmo_auth_register(struct osmo_auth_impl *impl) |
| { |
| if (impl->algo >= ARRAY_SIZE(selected_auths)) |
| return -ERANGE; |
| |
| llist_add_tail(&impl->list, &osmo_auths); |
| |
| /* check if we want to select this implementation over others */ |
| if (!selected_auths[impl->algo] || |
| (selected_auths[impl->algo]->priority > impl->priority)) |
| selected_auths[impl->algo] = impl; |
| |
| return 0; |
| } |
| |
| /*! Load all available authentication plugins from the given path |
| * \param[in] path Path name of the directory containing the plugins |
| * \returns number of plugins loaded in case of success, negative in case of error |
| * |
| * This function will load all plugins contained in the specified path. |
| */ |
| int osmo_auth_load(const char *path) |
| { |
| /* load all plugins available from path */ |
| #if !defined(EMBEDDED) |
| return osmo_plugin_load_all(path); |
| #else |
| return -1; |
| #endif |
| } |
| |
| /*! Determine if a given authentication algorithm is supported |
| * \param[in] algo Algorithm which should be checked |
| * \returns 1 if algo is supported, 0 if not, negative error on failure |
| * |
| * This function is used by an application to determine at runtime if a |
| * given authentication algorithm is supported or not. |
| */ |
| int osmo_auth_supported(enum osmo_auth_algo algo) |
| { |
| if (algo >= ARRAY_SIZE(selected_auths)) |
| return -ERANGE; |
| |
| if (selected_auths[algo]) |
| return 1; |
| |
| return 0; |
| } |
| |
| /* 3GPP TS 33.102 §6.8.2.3 C5 function to derive UMTS IK from GSM Kc */ |
| static inline void c5_function(uint8_t *ik, const uint8_t *kc) |
| { |
| unsigned int i; |
| |
| for (i = 0; i < 4; i++) |
| ik[i] = kc[i] ^ kc[i+4]; |
| memcpy(ik+4, kc, 8); |
| for (i = 12; i < 16; i++) |
| ik[i] = ik[i-12]; |
| } |
| |
| /* 3GPP TS 33.102 §6.8.2.3 C4 function to derive UMTS CK from GSM Kc */ |
| void osmo_c4(uint8_t *ck, const uint8_t *kc) |
| { |
| memcpy(ck, kc, 8); |
| memcpy(ck+8, kc, 8); |
| } |
| |
| /*! Generate 3G CK + IK from 2G authentication vector |
| * \param vec Authentication Vector to be modified |
| * \returns 1 if the vector was changed, 0 otherwise |
| * |
| * This function performs the C5 and C4 functions to derive the UMTS key |
| * material from the GSM key material in the supplied vector, _if_ the input |
| * vector doesn't yet have UMTS authentication capability. |
| */ |
| int osmo_auth_3g_from_2g(struct osmo_auth_vector *vec) |
| { |
| if ((vec->auth_types & OSMO_AUTH_TYPE_GSM) && |
| !(vec->auth_types & OSMO_AUTH_TYPE_UMTS)) { |
| c5_function(vec->ik, vec->kc); |
| osmo_c4(vec->ck, vec->kc); |
| /* We cannot actually set OSMO_AUTH_TYPE_UMTS as we have no |
| * AUTN and no RES, and thus can only perform GSM |
| * authentication with this tuple. |
| */ |
| return 1; |
| } |
| |
| return 0; |
| } |
| |
| /*! Generate authentication vector |
| * \param[out] vec Generated authentication vector |
| * \param[in] aud Subscriber-specific key material |
| * \param[in] _rand Random challenge to be used |
| * \returns 0 on success, negative error on failure |
| * |
| * This function performs the core cryptographic function of the AUC, |
| * computing authentication triples/quintuples based on the permanent |
| * subscriber data and a random value. The result is what is forwarded |
| * by the AUC via HLR and VLR to the MSC which will then be able to |
| * invoke authentication with the MS |
| */ |
| int osmo_auth_gen_vec(struct osmo_auth_vector *vec, |
| struct osmo_sub_auth_data *aud, |
| const uint8_t *_rand) |
| { |
| struct osmo_auth_impl *impl = selected_auths[aud->algo]; |
| int rc; |
| |
| if (!impl) |
| return -ENOENT; |
| |
| rc = impl->gen_vec(vec, aud, _rand); |
| if (rc < 0) |
| return rc; |
| |
| memcpy(vec->rand, _rand, sizeof(vec->rand)); |
| |
| return 0; |
| } |
| |
| /*! Generate authentication vector and re-sync sequence |
| * \param[out] vec Generated authentication vector |
| * \param[in] aud Subscriber-specific key material |
| * \param[in] auts AUTS value sent by the SIM/MS |
| * \param[in] rand_auts RAND value sent by the SIM/MS |
| * \param[in] _rand Random challenge to be used to generate vector |
| * \returns 0 on success, negative error on failure |
| * |
| * This function performs a special variant of the core cryptographic |
| * function of the AUC: computing authentication triples/quintuples |
| * based on the permanent subscriber data, a random value as well as the |
| * AUTS and RAND values returned by the SIM/MS. This special variant is |
| * needed if the sequence numbers between MS and AUC have for some |
| * reason become different. |
| */ |
| int osmo_auth_gen_vec_auts(struct osmo_auth_vector *vec, |
| struct osmo_sub_auth_data *aud, |
| const uint8_t *auts, const uint8_t *rand_auts, |
| const uint8_t *_rand) |
| { |
| struct osmo_auth_impl *impl = selected_auths[aud->algo]; |
| int rc; |
| |
| if (!impl || !impl->gen_vec_auts) |
| return -ENOENT; |
| |
| rc = impl->gen_vec_auts(vec, aud, auts, rand_auts, _rand); |
| if (rc < 0) |
| return rc; |
| |
| memcpy(vec->rand, _rand, sizeof(vec->rand)); |
| |
| return 0; |
| } |
| |
| static const struct value_string auth_alg_vals[] = { |
| { OSMO_AUTH_ALG_NONE, "None" }, |
| { OSMO_AUTH_ALG_COMP128v1, "COMP128v1" }, |
| { OSMO_AUTH_ALG_COMP128v2, "COMP128v2" }, |
| { OSMO_AUTH_ALG_COMP128v3, "COMP128v3" }, |
| { OSMO_AUTH_ALG_XOR, "XOR" }, |
| { OSMO_AUTH_ALG_MILENAGE, "MILENAGE" }, |
| { 0, NULL } |
| }; |
| |
| /*! Get human-readable name of authentication algorithm */ |
| const char *osmo_auth_alg_name(enum osmo_auth_algo alg) |
| { |
| return get_value_string(auth_alg_vals, alg); |
| } |
| |
| /*! Parse human-readable name of authentication algorithm */ |
| enum osmo_auth_algo osmo_auth_alg_parse(const char *name) |
| { |
| return get_string_value(auth_alg_vals, name); |
| } |
| |
| const struct value_string osmo_sub_auth_type_names[] = { |
| { OSMO_AUTH_TYPE_NONE, "None" }, |
| { OSMO_AUTH_TYPE_GSM, "GSM" }, |
| { OSMO_AUTH_TYPE_UMTS, "UMTS" }, |
| { 0, NULL } |
| }; |
| |
| /* Derive GSM AKA ciphering key Kc from UMTS AKA CK and IK (auth function c3 from 3GPP TS 33.103 § |
| * 4.6.1). |
| * \param[out] kc GSM AKA Kc, 8 byte target buffer. |
| * \param[in] ck UMTS AKA CK, 16 byte input buffer. |
| * \param[in] ik UMTS AKA IK, 16 byte input buffer. |
| */ |
| void osmo_auth_c3(uint8_t kc[], const uint8_t ck[], const uint8_t ik[]) |
| { |
| int i; |
| for (i = 0; i < 8; i++) |
| kc[i] = ck[i] ^ ck[i + 8] ^ ik[i] ^ ik[i + 8]; |
| } |
| |
| /*! @} */ |